Definition df-bj-cchat 36621

Description: Define the complex projective line, or Riemann sphere. (Contributed by BJ, 27-Jun-2019.)

Assertion

Ref	Expression
df-bj-cchat	⊢ ℂ̂ = (ℂ ∪ {∞})

Detailed syntax breakdown of Definition df-bj-cchat

Step	Hyp	Ref	Expression
1		ccchat 36620	. 2 class ℂ̂
2		cc 11110	. . 3 class ℂ
3		cinfty 36618	. . . 4 class ∞
4	3	csn 4623	. . 3 class {∞}
5	2, 4	cun 3941	. 2 class (ℂ ∪ {∞})
6	1, 5	wceq 1533	1 wff ℂ̂ = (ℂ ∪ {∞})

This definition is referenced by:  bj-rrhatsscchat  36624